This invention relates to retractable lamps, for example, head lamps or head lights of a motor vehicle, and more particularly, a driving mechanism for pivotally driving the retractable lamp to be selectively housed in or exposed from the outer surface of the body concerned.
Referring now to FIG. 1, there is shown a conventional driving mechanism for selectively housing or exposing the retractable lamp.
Conventionally, a base portion of a head lamp b of the above described type is pivotally mounted on a bracket secured to a body a, and the bottom portion of the head lamp b is relatively connected to a portion of the conventional driving mechanism c. More specifically, the bottom portion of the head lamp b is pivotally connected to one end of a rod d, the other end of which is further connected to one end of a link e. The link e has the other end mounted on the shaft of a worm wheel h which in turn is driven by a conventional arrangement comprising an electric motor f and a worm g secured to the main spindle of the electric motor f, as illustrated in FIG. 1. Furthermore, a lamp cover i and a pair of stop to prevent excess pivotal movement of the head lamp b, i.e., a stop k to prevent the head lamp b from being moved to far into the body and a stop j to prevent the reverse excess movement of the head lamp b are provided.
By the conventional arrangement described in the foregoing, the housing and exposing operations of the head lamp are accomplished in a manner as described hereinbelow.
After being pivotally driven following the rotational movement of the worm wheel h caused by the worm wheel-worm engagement when the electric motor f is driven, the link e causes the head lamp b to be pivotally moved through the pivotal movement of the rod d.
More specifically, when the link e is pivotally moved counterclockwise, the link e draws the rod d to the right in FIG. 1 and thereby, the head lamp is successively, pivotally moved counterclockwise with respect to the body a, whereby the head lamp b is in the body a housed. On the contrary, the head lamp b is exposed from the outer surface of the body a when the link e is pivotally moved in the reverse direction.
As is clear from the foregoing description, the movement for causing the head lamp to be properly disposed in the housed state or in the exposed state provided by the conventional driving mechanism requires a well-defined special arrangement for the control system associated with the electric motor so as to provide an accurate stopping actuation of the electric motor and thereby to prevent the excess movement of the head lamp.
Therefore, without a special arrangement for the control system mentioned above, the accomplishment of proper disposition of the head lamp is generally quite difficult, and naturally, deviation from the predetermined stopping position of the electric motor cannot be avoided. The deviation bring about a resultant deviation of the position of the optical axis of the head lamp from the desired position of 1 to 2 degrees. Since the permissible deviation in this angle is generally required to be less than 0.6 degrees, a resultant angular deviation of 1 to 2 degrees is too large to be allowed in a practical arrangement of the retractable head lamps. For decreasing the deviation mentioned above, although improvement in the accuracy of the control system associated with the electric motor will naturally cause the motor to be properly actuated in a predetermined manner, the arrangement needed to achieve such an improvement is generally quite expensive.